LYDSY Education Online Judge was the online judge of HengYang No.8 High School, so it is also called BZOJ. It is famous for the high-qualified problems in it. Most students attending NOIp will choose BZOJ as an advanced training session. It is said that more problems you solve in BZOJ, farther you go on the road of Olympiad in Informatics. However, it is also famous for its ugly user interface and the competence. Without donating BZOJ, you are not allowed to view or solve some problems. Usually, these problems are the best ones. So many people complain about that you can only get the competence by paying them money. But anyway, it is a high-qualified online judge.